The invention relates generally to a conversion machine and a method for converting sheet stock material into a cushioning product. More particularly, the machine and method produce a cushioning surface wrap.
In the process of shipping an item from one location to another, a protective packaging material is typically placed in the shipping container to fill any voids and/or to cushion the item during the shipping process. Some commonly used protective packaging materials are plastic foam peanuts and plastic bubble wrap. While these conventional plastic materials seem to perform adequately as cushioning products, they are not without disadvantages. Perhaps the most serious drawback of plastic bubble wrap and/or plastic foam peanuts is their effect on our environment. Quite simply, these plastic packaging materials are not biodegradable and thus they cannot avoid further multiplying our planet""s already critical waste disposal problems. The non-biodegradability of these packaging materials has become increasingly important in light of many industries adopting more progressive policies in terms of environmental responsibility.
The foregoing and other disadvantages of conventional plastic packaging materials have made paper protective packaging material a very popular alterative. Paper is biodegradable, recyclable and composed of a renewable resource; making it an environmentally responsible choice for conscientious companies.
While paper in sheet form could possibly be used as a protective packaging material, it is usually preferable to convert the sheets of paper into a relatively low density pad cushioning dunnage product. This conversion may be accomplished by a cushioning conversion machine, such as those disclosed in U.S. Pat. No. 4,968,291, U.S. Pat. No. 5,123,889 or European Patent Application No. 94440027.4. Such a cushioning conversion machine includes a frame having an upstream end and a downstream end, a stock supply assembly which supplies a continuous web of the sheet stock material, a conversion assembly which converts the sheet stock material into a continuous strip of a cushioning product, and a severing assembly which cuts the strip into sections of a desired length. The conversion assembly includes a folding or forming assembly which inwardly folds the lateral edges of the sheet stock material and a feed assembly which contacts a central section of the folded stock material. With particular reference to the machine disclosed in European Patent Application No. 94440027.4, the feed assembly crumples the folded portions of the stock material.
These earlier cushioning conversion machines produce a cushioning product having lateral pillow portions and a thinner central connecting portion. Such cushioning products are used to fill the voids between the item to be shipped and its container. However, in some packaging situations, a xe2x80x9cflatterxe2x80x9d cushioning product, or a product having less loft, may be more appropriate. For example, a xe2x80x9cflatterxe2x80x9d cushioning product may be more advantageous for placement between relatively flat items, such as plates and/or for the individual xe2x80x9csurface wrappingxe2x80x9d of articles such as fragile ornaments, glass hurricane lamps or the wooden legs on fine furniture. It would be desirable to have a flatter cushioning product with the flexibility to wrap around fragile and unusually shaped objects and which still functions to cushion and/or protect the object from damage.
The present invention provides a novel cushioning conversion machine and method which may be used to produce a xe2x80x9cflatterxe2x80x9d cushioning product or surface wrap than those produced by prior machines and methods. Additionally or alternatively, the present invention provides a cushioning conversion machine/method in which the sheet stock material is supplied in lengths related to the desired length of the cushioning product whereby a severing assembly is not necessary.
According to one aspect of the invention, the cushioning conversion machine includes a plurality of laterally spaced apart upstream assemblies which advance the sheet stock material with a transversely reciprocating motion and at least one downstream assembly which retards the advance of the stock material. The upstream assemblies feed the sheet stock material at a feed rate greater than the feed rate at which the downstream assembly passes the sheet stock material. The downstream assembly thereby cooperates with the upstream assemblies to crumple the stock material and impart loft thereto.
In a preferred embodiment of the invention, each upstream assembly includes a support wheel and a feed wheel. The feed wheel has an annular rib thereon which fits within an annular groove in the support wheel. The support wheel of each upstream assembly has axial end portions on either side of the annular groove, and each axial end portion has a plurality of flat faces alternating with arcuate areas about the circumference thereof. The flat faces of one axial end portion preferably are transversely aligned with the arcuate areas of the other axial end portion, and the arcuate areas may have a friction enhanced surface.
Further in accordance with a preferred embodiment of the invention, each downstream assembly includes a support wheel and a compression wheel. The support wheel has a friction enhanced surface for gripping the crumpled stock material and creasing the folds against the compression wheel.
The cushioning conversion machine may also include a stock supply assembly adapted to supply the sheet stock material in lengths related to a desired length of the cushioning product. Alternatively or additionally, the cushioning conversion machine may include a stock supply assembly adapted to supply a continuous web of the sheet stock material from which the upstream and downstream assemblies will produce a continuous web having crumpled portions. The cushioning conversion machine may also include a severing assembly for severing the continuous web into sections of a desired length.
According to another aspect of the invention, a cushioning conversion machine for converting sheet stock material into cushioning products of a desired length includes a conversion assembly which converts discrete lengths of sheet stock material into cushioning products. The conversion assembly includes a plurality of laterally spaced apart upstream assemblies which feed the stock material with a transversely reciprocating twisting action and at least one downstream assembly which retards the advance of the stock material. The downstream assembly cooperates with the upstream assemblies to crumple discrete lengths of the stock material and impart loft thereto.
According to another aspect of the invention, a method of making a cushioning product from sheet stock material includes the steps of: advancing the sheet stock material through a plurality of laterally spaced apart upstream assemblies in a transversely reciprocating manner; and retarding the advancement of the stock material through at least one downstream assembly downstream of the upstream assemblies. In this way the stock material becomes crumpled through the cooperation of the advancing and retarding steps.
As is preferred, the upstream assemblies operate to feed the sheet stock material at a feed rate greater than the feed rate at which the downstream assembly operates to feed or pass the sheet stock material therethrough. As is also preferred, the retarding step includes creasing the crumpled stock material so that the cushioning product retains a crumpled resilient state.
According to another aspect of a preferred method, a supplying step may include supplying sheet stock material having lengths related to a desired length of the cushioning product. Alternatively, the supplying step may include supplying sheet stock material as a continuous web whereby the converting step will produce a continuous web having crumpled portions. The method may also include the step of severing the continuous web into sections of a desired length.
As is preferred, the sheet stock material is biodegradable, recyclable, and made from a renewable resource. Most preferably, the sheet stock material is paper, and more particularly, Kraft paper, and is composed of a plurality of superimposed plies of Kraft paper.
The invention also provides a surface wrap produced by the conversion machine and/or method described above. In addition, there is provided a method of surface wrapping an article for cushioning purposes, such method including the step of wrapping the surface wrap around the surface of the article.
A preferred embodiment of surface wrap according to the invention includes a flat sheet stock material having a plurality of narrow, compressed feeding trails alternating with wide cushioning crumpled zones having a plurality of folds. The folds in the crumpled zones include a somewhat regular arrangement of folds preferably forming a herringbone pattern.
The foregoing and other features of the invention are hereinafter fully described and particularly pointed out in the claims, the following description and annexed drawings setting forth in detail certain illustrative embodiments of the invention, these embodiments being indicative, however, of but a few of the various ways in which the principles of the invention may be employed.